The present preferred embodiment concerns a method and a device for scanning images, wherein a source image is scanned by means of multiple color sensor elements. The source image can be both a black-and-white image and a color image. The target image generated by the scanning is a black-and-white image.
It is known that black-and-white images can be scanned with a color scanner that possesses multiple color sensor elements. The source image is hereby typically scanned in the same manner as a color image, and the pseudo-color image so obtained is correspondingly corrected so that the grey levels in the target image coincide optimally well with the corresponding brightness values in the source image. In these known methods, black-and-white images are scanned with the same speed and with the same resolution as color images.
A method for scanning images by means of a device that possesses multiple color sensors in order to generate a target image as a black-and-white image emerges from the European Patent Application PCT/EP2005/012882 (not yet published). In this device, the scanning speed and/or the resolution are increased relative to conventional methods. The fundamental difference of this method relative to the conventional methods lies in that individual image points (pixels) of the source image are not respectively scanned by all color sensor elements, but rather only by a respective single color sensor element, whereby it is possible that the multiple color spin echo sequence simultaneously scan multiple pixels. The scanning speed is hereby increased or a significantly higher resolution is achieved given the same scanning speed as in conventional scanning devices.
Since the individual color sensor elements generate different signals for the same brightness values, the signals are correspondingly corrected. Upon scanning a color source image, color regions of the source image are registered with differing strength with the different color sensor elements. A red, green and blue color sensor element is normally provided. A green color region in the source image is detected well by the green color sensor element, in contrast to which the blue and red color sensor elements emit barely any signal for a green color region. Flaws (which are designated as frequency artifacts) hereby arise in the target image of a color source image. Such frequency artifacts can be detected and corrected with corresponding filters.
In this method, the pixels acquired with the different color sensor elements are initially sorted so that they are arranged in an arrangement corresponding to the source image. This is necessary since the different sensor elements are arranged at a distance from one another, such that here a data stream in which the values of the individual pixels are arranged offset relative to one another from data stream to data stream arises for each sensor element.
A method for interpolation and correction of a digital image emerges from the international Patent Application WO 2005/114573 A1 corresponding to pending U.S. application Ser. No. 11/579,293, wherein a source image is mapped to a target image with a FIR filter. The FIR filter comprises multiple filter coefficients that contain both the information regarding interpolation and regarding correction of the image. Both the interpolation and the correction of the image are hereby executed in a single step.